Top side venting of lightweight concrete in roof systems

ABSTRACT

An assembly and method for venting a flat or low sloped roof system eliminates the need for a base sheet membrane and fasteners and provides a spaced arrangement of V-grooves formed in the top surface of a new or existing lightweight concrete deck. The V-grooves allow moisture to migrate to the perimeter of the roof and exit the roof system. Instead of attaching a base sheet membrane to the lightweight concrete deck using penetrating fasteners, the roof membrane plies are attached directly to the primed lightweight concrete deck by self-adhesion, heat welding or with the use of cold adhesives. This prevents damage to the structural integrity of the underlying lightweight concrete, while providing an improved roof venting system.

This non-provisional patent application is based on provisional patentapplication Ser. No. 60/778,204 filed on Mar. 2, 2006. Applicant claimsthe benefit of the provisional patent application filing date underTitle 35, United States Code section 119(e).

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to roofing systems, and, more particularly, toroofing systems that use lightweight insulating concrete with an overlyinter-ply sheet and cap membrane on flat or low sloped roof areas.

2. Discussion of the Related Art

Generally, roof systems that use lightweight concrete with or withoutinsulation require a base sheet membrane to be mechanically installed tothe lightweight concrete for the purpose of allowing moisture tomigrate. Once the base sheet is mechanically attached to the lightweightconcrete, additional layers of roofing membrane are attached to the basesheet by either self adhesive, heat weld or cold adhesive. This bondsthe membranes together to make up the roof assembly. Despite thewidespread use of the mechanically attached base sheet membrane, used inflat and low sloped roof systems, there are significant drawbacksassociated with its use. In particular, the increased amount ofpenetrating fasteners that need to be installed in order to meet thewind uplift requirements actually damage the lightweight the concrete atcorners and along the perimeter of the roof. The resultant damage to thelightweight concrete, caused by the closely spaced fasteners, eventuallyleads to deck failure. Furthermore, when the roof needs to be replaced,requiring removal of the base sheet and fasteners, holes are left in thelightweight concrete. Thereafter, a new base sheet membrane isinstalled, and new fasteners penetrate additional areas of the existinglightweight concrete deck. Consequently, further damage is caused to thelightweight concrete deck.

It should be noted that the benefit of using lightweight concrete inlieu of insulation is not only to provide a slope for the roof system,but also to provide the owner with an insulating system that will remainintact after re-roofing and continue to provide the owner the slope andinsulating value for all future roof systems.

In view of these shortcomings of the traditional mechanically attachedbase sheet membrane, there exists an urgent need in the roofing industryfor an alternative venting system for new and existing lightweightconcrete deck structures which overcomes the above described problems.More specifically, there is a need for a venting system that will allowmoisture to travel to the perimeter of the roof, where the moisture canexit the roof assembly thru an A.R.B.S. (Alternative Roof BlockingSystem) of the type disclosed in U.S. Pat. No. 6,237,293 B1. Further,there is a need for venting the top side of a new or existinglightweight concrete deck which will considerably reduce costs for laborand material by eliminating the installation of the base sheet membraneand fasteners that are currently required for attachment to thelightweight concrete deck.

OBJECTS AND ADVANTAGES OF THE INVENTION

A primary object of the present invention is to eliminate the use of themechanically attached base sheet currently used in flat or low slopedroof systems and to provide the new or existing lightweight concretewith V-grooves on the top surface which replace the function of the basesheet and allow the venting of moisture to travel to the roof perimeterand exit the roof system.

It is a further object of the present invention to provide necessary topside venting of a new or existing lightweight concrete roof deck withoutcompromising the structural integrity of the lightweight system that ispresently caused by installation of the base sheet membrane withmechanical fasteners that penetrate the lightweight concrete.

It is still a further object of the present invention to provide ventingmeans in a low-sloped roof system which will release heat and moisturethrough an arrangement of V-grooves formed in the top side of alightweight concrete deck.

SUMMARY OF THE INVENTION

The present invention is directed to an improved roof venting systemthat eliminates the need of a base sheet membrane that is presently usedand that is mechanically attached with fasteners to new or existinglightweight concrete. An improved venting system is achieved byinstalling an arrangement of V-grooves during the installation of newlightweight concrete. The V-grooves are approximately ½ inch to 1 inchdeep and are spaced at approximately 3 to 12 inches apart. The V-groovesare installed during the finishing of the top coat using a 4 inch wideby 4 foot long aluminum flat bar having V-groove forming blades weldedto bottom side of the tool. The V-groove blades are installed 3 incheson center, 6 inches on center or 12 inches on center, depending on theindividual venting needs on new lightweight concrete. On existinglightweight concrete, the V-grooves are cut into the top surface of thelightweight concrete deck with a carbine blade. The V-grooves allow heatand moisture to migrate to the perimeter of the roof and out the ventholes of an A.R.B.S. (Alternative Roof Blocking System) of the typedisclosed in U.S. Pat. No. 6,237,293 B1.

BRIEF DESCRIPTIONS OF THE DRAWINGS

For a fuller understanding of the nature of the present invention,reference should be made to the detailed description taken inconjunction with the accompanying drawings in which:

FIG. 1 is a partial perspective view of the lightweight concrete overstructural decking having V-grooves installed in the top side oflightweight concrete in order to provide venting for flat or low slopedroof systems without the use of a mechanically attached base sheet; and

FIG. 2 is a partial perspective view showing the roof system of FIG. 1and illustrating formation of the V-Grooves in the top side of thelightweight concrete by raking with a tool.

Like reference numerals refer to like parts throughout the several viewsof the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The improved venting system of the present invention is used inconjunction with a low sloped or flat roof system of the type which useslightweight insulating concrete. Referring to FIG. 1 and 2, a roofsystem 10 is applied to a structural roof deck 100 of a building. Thesystem includes a lightweight insulating concrete deck comprising a baselayer of lightweight concrete 20, EPS Holey board insulation 22 and atop layer of lightweight concrete 24. The venting system of the presentinvention is achieved by installing a series of parallel V-grooves 30 onthe top side 26 of the top coat 24 of lightweight concrete. TheV-grooves 30 are spaced between 3 inches and 12 inches apart on centerand are preferably between ½ inch to 1 inch deep. When new lightweightconcrete is being installed, the V-grooves are formed during thefinishing of the top coat 24 using a rake tool 50, as seen in FIG. 2. Ina preferred embodiment, the rake tool 50 has a 4 inch wide by 4 footlong aluminum flat bar 22 having an arrangement of spaced V-grooveforming blades 54 on the bottom side. While not shown, the rake tool 50preferably has an elongate pole with a handle. The pole is fixed to theflat bar and extends upwardly at an angle to facilitate ease of use. Therake 50 is dragged across the top coat 24 to form the V-grooves 30 inthe top side 26. On existing lightweight concrete, the V-grooves are cutinto the top side 26 with the use of a carbine blade on a rotary saw.

Once the V-grooves 30 are formed in the top side 26, one or more layersof roof membrane 58 are attached to the top side of the lightweightinsulating concrete deck. The one or more roof membrane plies 58 areattached to the top side 26 by self adhesion, heat welding or with theuse of cold adhesives.

The V-grooves 30 allow heat and moisture to migrate (i.e., within thegrooves 30) to the perimeter of the low sloped roof and to release outthrough vent holes of an A.R.B.S. (Alternative Roof Blocking System) 60,as seen in FIG. 1.

While the present invention has been shown and described in accordancewith preferred and practical embodiments thereof, it is recognized thatdepartures from the instant disclosure are contemplated within thespirit and scope of the invention.

1. A roof system for installation on a roof structure of a buildingcomprising: a lightweight insulating concrete deck applied on the roofstructure, and said lightweight insulating concrete deck including a topsurface; an arrangement of grooves formed in said top surface of saidlightweight insulating concrete deck, and said grooves being structuredand disposed for directing moisture and liquid to the perimeter of theroof structure; and at least one layer of roof membrane attached to saidtop surface of said lightweight insulating concrete deck.
 2. The roofsystem as recited in claim 1 wherein said grooves are arranged inspaced, parallel relation on said top surface of said lightweightinsulating concrete deck.
 3. The roof system as recited in claim 1wherein said grooves are at least 0.5 inch deep.
 4. The roof system asrecited in claim 1 wherein said grooves are between a 0.5 inch and 1.0inch deep.
 5. The roof system as recited in claim 1 wherein said groovesare arranged at spaced, parallel intervals of between 3 inches and 12inches apart.
 6. The roof system as recited in claim 1 wherein said atleast one layer of roof membrane is attached directly to said topsurface of said lightweight insulating concrete deck by self adhesion.7. The roof system as recited in claim 1 wherein said at least one layerof roof membrane is attached directly to said top surface of saidlightweight insulating concrete deck by heat welding.
 8. The roof systemas recited in claim 1 wherein said at least one layer of roof membraneis attached directly to said top surface of said lightweight insulatingconcrete deck by a cold adhesive.
 9. The roof system as recited in claim1 further comprising: a plurality of layers of roof membrane attacheddirectly to said top surface of said lightweight insulating concretedeck.
 10. A roof system for installation on a roof structure of abuilding comprising: a lightweight insulating concrete deck applied onthe roof structure, and said lightweight insulating concrete deckincluding a top surface; an arrangement of grooves formed in said topsurface of said lightweight insulating concrete deck, each of saidgrooves having a V-shaped cross-sectional configuration and said groovesbeing structured and disposed for directing heat and moisture to theperimeter of the roof structure; and at least one layer of roof membraneattached to said top surface of said lightweight insulating concretedeck.
 11. The roof system as recited in claim 10 wherein said groovesare between 0.5 inch and 1.0 inch deep.
 12. The roof system as recitedin claim 10 wherein said grooves are arranged at spaced intervals ofbetween 3 inches and 12 inches apart.
 13. The roof system as recited inclaim 10 wherein said at least one layer of roof membrane is attacheddirectly to said top surface of said lightweight insulating concretedeck by self adhesion.
 14. The roof system as recited-in claim 10wherein said at least one layer of roof membrane is attached directly tosaid top surface of said lightweight insulating concrete deck by heatwelding.
 15. The roof system as recited in claim 10 wherein said atleast one layer of roof membrane is attached directly to said topsurface of said lightweight insulating concrete deck by a cold adhesive.16. The roof system as recited in claim 10 further comprising: aplurality of layers of roof membrane attached directly to said topsurface of said lightweight insulating concrete deck.
 17. A method forventing a flat or low sloped roof system comprising the steps of:applying a lightweight insulating concrete deck to the top roof deckstructure on a building; forming an arrangement of grooves in a topsurface of said lightweight insulating concrete deck; and attaching atleast one layer of roof membrane directly to said top surface of saidlightweight insulating concrete deck.
 18. The method as recited in claim17 wherein said step of forming said arrangement of grooves in said topsurface further comprises: moving a rake having a plurality of grooveforming blades over said top surface of said lightweight insulatingconcrete deck during a finishing step of applying said lightweightinsulating concrete deck to the top roof deck structure.
 19. The methodas recited in claim 17 wherein said step of forming said arrangement ofgrooves in said top surface further comprises the step of: cutting saidarrangement of grooves with a rotary saw.
 20. The method as recited inclaim 17 wherein in each of the grooves in said arrangement of grooveshas a V-shaped cross-sectional configuration and a depth ranging between0.5 inch and 1.0 inch.